1. Field of the Invention
This invention relates to a roll-shaped mold for forming an information recording medium to be used for formation of grooves for a track of an information recording medium by roll-to-roll continuous molding.
2. Related Background Art
In the prior art, an information recording medium performs recording and reproduction by light, for example, a laser beam, when grooves for a track which serve to guide the laser beam for recording and/or reproduction on a plastic substrate by heat molding, such as compression, extrusion molding or injection molding, a flat plate stamper has been used as the stamper. Its production method comprises forming a photoresist film subjected to patterning by irradiating a laser beam onto a photoresist film coated on a glass plate followed by developing, and subsequently repeating nickel electroforming for plural times with the use of the photoresist film as the original mold to obtain an electroformed mold having the pattern transferred thereon, which is pressed as the stamper on a substrate to form grooves for the track. For example, as disclosed in Japanese Laid-open Patent Application No. 236049/1986, a glass original plate having unevenness signals recorded directly thereon has been known as the stamper for disc molding.
However, the system of forming grooves for track of information recording medium by use of a mold of the flat plate stamper of the prior art is not suitable for a production system which aims at low cost.
For example, it is difficult to use a flat plate stamper for forming grooves for track according to continuous steps such as the roll-to-roll system.
As the method for solving these problems, Japanese Laid-open Patent Application No. 86721/1981 discloses a method for producing information recording discs in a large amount at low cost by the roll-to-roll system by molding acoustic grooves of a thermoplastic resin with molding rolls.